Abstract
BackgroundFriedreich ataxia is the most frequent hereditary ataxia worldwide. Subclinical visual and auditory involvement has been recognized in these patients, with co-occurrence of severe blindness and deafness being rare.Case reportWe describe a patient, homozygous for a 873 GAA expansion in the FXN gene, whose first symptoms appeared by the age of 8. At 22 years-old he developed sensorineural deafness, and at 26 visual impairment. Deafness had a progressive course over 11 years, until a stage of extreme severity which hindered communication. Visual acuity had a catastrophic deterioration, with blindness 3 years after visual impairment was first noticed. Audiograms documented progressive sensorineural deafness, most striking for low frequencies. Visual evoked potentials disclosed bilaterally increased P100 latency. He passed away at the age of 41 years old, at a stage of extreme disability, blind and deaf, in addition to the complete phenotype of a patient with Friedreich ataxia of more than 30 years duration.DiscussionSevere vision loss and extreme deafness has been described in very few patients with Friedreich ataxia. Long duration, severe disease and large expanded alleles may account for such an extreme phenotype; nonetheless, the role of factors as modifying genes warrants further investigation in this subset of patients.
Highlights
Friedreich ataxia is the most frequent hereditary ataxia worldwide
Severe vision loss and extreme deafness has been described in very few patients with Friedreich ataxia
We report the rare occurrence of blindness and deafness as part of an extreme Friedreich ataxia (FRDA) phenotype
Summary
The first description of optic atrophy in FRDA was made by Sjögren, in 1940, in 12% of his patients [2]. A few studies have demonstrated that subclinical involvement of visual and auditory systems is much more frequent than severe blindness and deafness [5,6,7]. A study on a mouse model, addressing retinal ganglion cell death, suggested that optic atrophy was a consequence of increased sensitivity to oxidative stress, due to impaired intra-cellular iron regulation [13]. With this report we wish to (1) further contribute to the characterization of optic and auditory involvement in FRDA, (2) stress the need to better understand the underlying mechanisms, as well as their genetic and epigenetic modifying factors (including somatic heterogeneity); and (3) increase awareness for this rare extreme phenotype.
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